Concrete beam forms

ABSTRACT

Apparatus for forming concrete beams integrally with concrete floors comprising an elongated beam form with bottom and side walls and with flanges extending outwardly from the top of the side walls. A pair of rods projected upwardly through holes in opposite flanges, are tied by a steel strap to prevent spreading of the side walls when concrete is poured into the form. After the concrete sets, the rods are pulled out, the form stripped, and the strap left in place. The elongated beam forms have end portions, where the lower walls are stepped down and the side walls stepped outwardly, and a pair of aligned beam forms is joined by an adjustment form section which lies within the stepped end portions of the beam forms.

Dashew et al.

CONCRETE BEAM FORMS [75] Inventors: Stephen S. Dashew, Los Angeles;Arnold Wills, Lakeview Terrace, both of Calif.

[73] Assignee: La Mesa Industries, Inc., Compton,

Calif.

[22] Filed: July 21, 1972 [21] Appl. No.: 273,737

Related U.S. Application Data [62] Division of Ser, No. 30,872, April22, 1972, Pat. No.

[52] U.S. Cl. 249/28, 249/48 [51] Int. Cl. E04g 11/42 [58] Field ofSearch 249/26, 28, 48, 49, 50, 17,

[56] References Cited UNITED STATES PATENTS 1,675,749 7/1928 Crawford249/26 1,282,200 10/1918 Des Lauriers 249/48 944,543 12/1909 DesLauriers.... 249/26 1,119,969 12/1914 Longevin 249/26 1,331,096 2/1920Eaches 249/26 1,143,107 6/1915 Des Lauriers.... 249/26 1,616,354 2/1927Comer 249/192 X .1451 Feb. 19,1974

Primary Examiner-J. Spencer Overholser Assistant Examiner.lohn S. BrownAttorney, Agent, or Firm-Lindenberg, Freilich & Wasserman [5 7 ABSTRACTApparatus for forming concrete beams integrally with concrete floorscomprising an elongated beam form with bottom and side walls and withflanges extending outwardly from the top of the side walls. A pair ofrods projected upwardly through holes in opposite flanges, are tied by asteel strap to prevent spreading of the side walls when concrete ispoured into the form. After the concrete sets, the rods are pulled out,the form stripped, and the strap left in place. The elongated beam formshave end portions, where the lower walls are stepped down and the sidewalls stepped outwardly, and a pair of aligned beam forms is joined byan adjustment form section which lies within the stepped end portions ofthe beam forms.

1 Claim, 10 Drawing Figures CONCRETE BEAM FORMS This is a division, ofapplication Ser. No. 30,872 filed Apr. 22, 1970, now US. Pat. No.3,735,953.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to concrete forming apparatus and methods, and moreparticularly, to forms and methods for producing concrete beamsintegrally with concrete floors or ceilings.

2. Description of the Prior Art Concrete floors with integral beams havegenerally been constructed by building plywood decks with gaps, andbuilding plywood troughs along the gaps to form the beams. In order toprevent spreading of the trough sides under the weight of the concrete,wires are inserted through the form to hold the trough sides together.Such wires, generally referred to as form ties, are inconvenient tothread through structural steel located in the beam region. In addition,the wires have the disadvantage that they generally are tapered topermit removal from the set concrete, which makes them expensive. Also,the patching of the holes left by the withdrawn wire is easily seen inthe finished structure, since the patches are located in the downwardlyextending beam.

A new beam-forming trough is constructed for each beam, and disassembledafter the beam is formed. This repeated construction of troughs out ofplywood and their disassembly, is time consuming and thereforeexpensive. However, it is resorted to because many different lengths ofbeams are used in the usual building, so it would be difficult torepeatedly use only one or a few forms. Also, a one-piece form thatenclosed the beam from below would be difficult to remove from the setconcrete. I

OBJECTS AND SUMMARY OF THE INVENTION An object of the present inventionis to provide forms for constructing concrete beams at building sites,which is more economical than forms available heretofore and whichprovides beams of better appearance.

Another object is to provide a method for constructing concrete beamswhich is more economical and which provides beams of better appearancethan heretofore.

In accordance with one embodiment of the present invention, beam formsare provided which have a bottom wall, side walls extending upwardlyfrom the bottom wall, and flanges extending outwardly from the top ofthe side walls. Pairs of rods can be projected upwardly through holes inthe opposite flanges to hold the ends of straps that brace the sidewalls against outward spreading when the form is filled with concrete.After the concrete is set, the rods are pulled out, the form removed,and the straps left in place in the floor region above the beam. Theholes from which the rods have been removed are patched, but the factthat these holes are in the ceiling near the beams makes the patcheshardly noticable.

In order to facilitate removal of the forms from set concrete, they mustbe flexible to permit the flanges to pivot down and the side walls tospread apart. However, in many cases, the walls also should be stiff tohold concrete without deflecting excessively. A fiberglass form isemployed that can bend, and its bottom wall, side walls and flanges arebraced by sheets of plywood. The corners of the form are left uncoveredby plywood so they can flex to permit the sides and flanges to deflectaway from the concrete during removal.

The beam forms are constructed to permit them to be used for beams ofvarious lengths, so that the same forms can be used many times inconstructing a building where almost all beams are of different lengths.To permit this, the beam forms have end portions with a down-steppedbottom wall and outstepped side walls. An adjustment form section isemployed to bridge the end portions of two aligned beam forms, theadjustment section lying on the down-stepped bottom walls and within theout-stepped side walls. The ends of the beam forms can be spaced fromeach other within a range of distances, and still can be bridged by theadjustment form. An adjustment form can be constructed as anintersection to connect four beam forms.

The novel features of the invention are set forth with particularity inthe appended claims. The invention'will be best understood from thefollowing description when read in conjunction with the accompanyingdrawmgs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view,partially sectional, of a beam form constructed in accordance with oneembodiment of the invention;

FIG. 2 is a sectional end view of the beam form of FIG. 1, shown afterthe pouring of concrete therein;

FIG. 3 is a partial side view of beam forms of the type shown in FIG. 2;

FIG. 3A is a side elevation view of the forms of FIG. 3, showing theirremoval from side concrete;

FIG. 4 is a plan view of a star intersection form for joining four beamforms of the type shown in FIG. 1;

FIG. 5 is a plan view of a form assembly for constructing an integralbeam and column;

FIG. 6 is a side elevation view of the form assembly of FIG. 5i

FIG. 7 is a sectional end view of a flexible beam form constructed inaccordance with another embodiment of the invention;

FIG. 8 is a view of the form of FIG. 7 after concrete has been pouredtherein; and

FIG. 9 is a view of theform of FIG. 8 during removal of the form fromset concrete.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, theinvention provides a beam form 10 which can form a concrete beam 12 thatis integral with a concrete floor 14. Most of the concrete floor I4 isformed by a deck 16 of plywood or the like, with elongated gaps thereinwhich can receive beam forms 10. After the deck and beam forms are inplace, and steel bars have been positioned, which are to remain in theset concrete to reinforce it, concrete is poured over the structures tofill the beam form and the region above the deck 16. When the concretesets, the deck 16 and beam form 10 must be stripped away, to leave aconcrete floor with integral beams. In many cases, the beams may be leftexposed in the finished building. After one floor is formed, the'nexthigher floor is formed by building another deck and positioning the beamforms along gaps in it. It should be understood that the term floor.refers to the type of structure rather than its use, and such structuresoften serve primarily as ceilings to cover a space.

The beam form includes a body 18 of a resilient material such asresin-impregnated fiberglass, that has been molded into the shape of apan with flanges. The body includes a lower or bottom wall 20, a pair ofside walls 22, 24 extending upwardly from either side of the bottomwall, and a pair of flanges 26, 28 extending outwardly from the top ofeach side wall. The fiberglass body 18 is resilient enough to bedeformed, and therefore, in some cases it must be stiffened to preventexcessive deflection or even failure under the weight of I concretepoured into it. Accordingly, stiff bracing members in the form of setsof plywood sheets 30, 32, 34, 36 and 38 are applied to the outsidesurfaces of the walls of the fiberglass body. The edges of the plywoodbracing sheets are spaced from each other to leave gaps at the cornersof the form, so that the side walls 22, 24 can be spread apart, and theflanges 26, 28 pivoted downwardly during removal of the beam form fromthe set concrete.

The ability of the form side walls to spread apart for removal,necessitates the use of means for holding the sides together during thepouring of concrete into the form. The great weight of concrete in theform would wires were tapered to facilitate their removal after theconcrete was formed. The concrete beams and floor generally includemazes of reinforcing steel bars and wires, some of which are shown at40, and the threading of numerous form wires through the reinforcingsteel members added to the cost of construction. Instead of using suchremovable form wires, straps 42 are employed as tensile members whichextend through the floor region of the concrete structure.

In accordance with the invention, means are provided to employ thestraps 42 to hold the beam form 10 against spreading under the weight ofconcrete poured therein. Accordingly, holes 44, 46 are provided in theflanges 26, 28 and flange bracing structures 36, 38 to permit theprojection of rods 48, 50 therethrough which can engage holes in thestrap 42. The rods 48, 50, which serve as tie holding members, are longbolts with reduced diameter ends 52 that can project through holes inthe strap 42. The flange structures, each composed of a flange 26 or 28and plywood sheets 36 or 38 thereunder, have plates 54 fixed to theirundersides, each plate carrying athreaded nut 56. The rods 48, 50 areeach threaded along a portion spaced from their tips, so that they canbe screwed into the nuts 56 and held in place. After the rods are thusinstalled, the strap 42 can be installed by laying it in place, with theholes atits ends engaged by the tips 52 of the rods.

' After the concrete floor structure with integral beams has been formedand the concrete has set,'the decks beneath the floors can be removedand the beam forms can be removed. Removal of a beam form isaccomplished by first removing the rods 48, 50. This is sides of theform outwardly. When the beam form 10 has been removed, the strap 42will still remain in place, and two holes will be present in the ceilingof the concrete structure where the two rods were removed. These holescan be patched, if desired. The fact that the holes are in the ceilingof the structure lessens the possibility of water seepage therein, andmakes then and any patchworkon them, less apparent than if the holeswere in the beam 12.

The size of the straps 42 can be fairly large, so that they can bespaced a considerable distance such as several feet apart along thelength of the beam forms. The large bracing force which the straps canprovide is reliably transmitted through the strong rods 48, 50, anddistributed by the strong flange structures to the sides of the beamform. Of course, a reduction in the number of rods and straps to beinstalled considerably lowers the amount of work required to install andremove them and to perform any patching of the holes they leave.

Generally, there is no standard length of beams between columns or otherend structures. In some buildings, columns of continually decreasingwidth are utilized so that the beams of successively higher stories inthe building are of successively longer length. If a different beam formhad to be employed for each different beam length, then a large numberof forms would have to be stocked and delivered to each building site.In order toeliminate the need for large numbers of forms of differentlengths, beam form apparatus is provided which facilitates adjustment ofbeam length. As shown in HO. 1 and 3, each beam form 10 has end portions60 wherein the bottom wall 20E of the fiberglass body is down-stepped,the opposite side wall 22E and 24E are out-stepped and the oppositeflanges 26E and 28E are down-stepped. As shown in FIG. 3, a pair of beamforms 10A and 108 may be aligned to construct a long beam, and anadjustment form section or form 62 can be employed to bridge the twobeam forms. The adjustment section 62 is essentially a short length of afiberglass beam form without down-stepped or outstepped ends, andwithout sheets of bracing plywood. The down-stepped and out-stepped endportions of the beam forms 10A and 10B are stepped only far enough sothat the upper surface 645 of the bottom wall 64 of the adjustment formsection is even with the upper surfaces 20S of the beam forms 10A and108. Similarly, the out-stepping of the side walls is just far enough toaccommodate the thickness of the adjustment section, and thedown-stepping of the flanges is just enough to accommodate the thicknessof the adjustment section flanges;

In order to prevent the leakage of concrete around the ends of theadjustment section, strips 66 and 68 of tape are applied to the innersurfaces of the intersection of the beam and adjustment forms. If thegap between the two beam forms 10A and 10B is large as compared to thelength of the adjustment section 62, the tape strips 66 and 68 wouldhave to cover a wide gap between the upper surfaces 205 of the beamforms and upper surface 643 of the adjustment section. The tape may notbe strong enough to support concrete across such a gap. In such a case,filler strips such as strip 70 can be laid in the gap, on the bottom andside walls and on the flanges. Thus, only a limited number of beam formsis required to construct concrete beams of a variety of lengths, byproviding adjustment sections which can lie in appropriately constructedend portions of the beam forms. Of course, it is possible to constructeach beam form with one end stepped in the manner described, and theother end plain. In that case, the plain end of each beam form would fitinto the stepped end of another form, so that no separate adjustmentform section would be required.

As shown in FIG. 3, the ends of the adjustment section 62 are tapered atan angle A such as 20 from the vertical (as seen in a side elevationview). Similarly, the ends of the forms A and 10B whichjoin to theadjustment section 62 are tapered'or inclined from the vertical. Suchinclining facilitates removal of the forms from set concrete, as shownin FIG. 3A, which illustrates two forms 10A and 10B and an adjustmentsection 62 extending between two columns 71, 73. A slight downwardmovement or pivoting of one form 10A to position 10A helps to free thatform from the column 71 and adjustment section 62, by creating a gapbetween formerly abutting surfaces.

The design used for the adjustment section can be employed to enable thejoining of more than two beam forms, as at an intersection of four formsshown in FIG. 4. As shown in that figure, and adjustment section in theshape of a star intersection 80 is provided to join four beam forms 10C,10D, 10E and 10F. The star intersection is a simple fiberglass formwhich is coupled to the ends of the beam forms in the same manner as theadjustment form section 62 described above. That is, the four ends ofthe star intersection are received in the down-stepped and out-steppedend portions of the beam forms, and tape strips 82 are employed to sealthe insides of the star intersection to the beam forms.

The ends of the beam forms can be constructed to provide a beam whichmerges into a column. FIGS. 5 and 6 illustrate a beam form 90 with anend 92 that partially encompasses a column region to form part of acylindrical column 94. A half-column form section 96 with flanges98extends l80 about the column. The flanges 98 on the half-column sectionare held by bolts 100 to corresponding flanges 102 on the beam form end92, to encircle the column region and connect it to the region which isto form the beam in the-foor. Typically, the column 94 has already beenformed to a height slightly above the bottom of the beam form 90, andthe end 92 of the beam form and the half-column section 96 are mountedabout this already-formed column portion. As with other joints, tapestrips are applied to seal the joints against leakage.

A concrete floor with integral beams is constructed by first setting upshoring as shown at 110 in FIG. 2, to support the beam forms and plywooddecks. The shoring may include pipes 112 with plates 114 at their upperends, and wooden beams 116 that support the deck 16 and beam form 10 inposition. The wooden beams 116 are generally placed so that they supportthe flanges and bottom walls of the beam forms. After the shoring hasbeen installed, the deck 16 may be constructed, with gaps left in it forreceiving the beam form. The beam form 10 is then lowered into positionuntil it rests on the wooden beams 116 which have been set up to holdit. The rods 48, 50 are then installed and the strap 42 is laid on them.Strips of tape 118 are then applied to seal the gap between the flangesand the deck. After the deck and forms have been thus installed, andreinforcing bars have been positioned over the deck and in the forms,concrete is poured above the deck and forms. When the concrete has set,the rods 48, 50 are removed, the shoring is removed, the decks 16 areremoved, and the form 10 is removed. The removal of the form 10 can beaccomplished by driving wedges between the ceiling of the concrete floor14 and the upper surface of the flanges 26, 28, while pulling down onthe beam form. Handling braces 120 can be provided to serve as graspingpositions that aid in pulling down the beam forms as well as inotherwise handling the forms, and also serve to strengthen the forms.The handling braces are beams of wood attached to the plywood sheets atthe sides of the forms, and are spaced at intervals of several feetalong the length of the forms. 7

Thus, the invention provides beam forms which can be rapidly installedand removed, and which produce concrete structures with less noticableinregularities such as patchings. A limited number of form sizes can beutilized in constructing a building with concrete beams of a largevariety of lengths, by the use of adjustment sections that permit smallchanges in beam length to be made using beam forms of a particularlength. The adjustment sections can be constructed for functions otherthan merely joining two aligned beams, such as in joining four beamstogether at an intersection. The beam forms can have a tapered orinclined end to facilitate removal and one end can be constructed toform part of a column. The beam forms are utilized in methods thatpermit rapid installation and removal of the form by simplifyingapparatus that holds the form sides against spreading. Thissimplification involves the use of straps positioned at the level of thefloor, the use of rods that project through the ceiling to hold thestraps, and the fact that the straps are left in the concrete.

FIGS. 7, 8 and 9 illustrate another embodiment of a beam form, which isconstructed with resilient side walls that are designed to be deformedslightly by the weight of concrete in them. This resilient deformationis utilized to facilitate removal of the form from set concrete. Theform 120' has a bottom wall 122, side walls 124, 126 and flanges 128,130. The side walls 124, 126 are constructed of a resilient materialsuch as fiberglass and of a thickness which results in appreciabledeformation when the form is filled with concrete. The deformationresults in the lower portion of the side walls bulging out to theconfiguration shown in FIG. 8, under the pressure of the concrete. I

Initially, the flanges 128, 130 are held against spreading by the straps132 and bolts 134. However, after the concrete sets and the bolts areremoved, the flanges and form sides are free to spread out. As shown inFIG. 9, the sides 124, 1 26 spread out until they substantially achievetheir original straight configuration. The bulge in the concrete nearthe lower part of the beam causes the sides to spread out, while theflexibility at the corners 136, 138 allows considerable spreading tooccur. The form 120' is then much easier to remove from the beam. It maybe necessary to apply wedges or the like to the form to free sides sothey can spring out to the configuration of FIG. 9, but the effort isless than is generally otherwise required. It may be noted that thebottom wall 122 does not have to deflect, and it can be stiffened byemploying an increased thickness or by plywood bracing sheets or thelike to prevent deformation.

The bulge in the beam is not greatly apparent since it is smooth andregular. For a fourteen inch wide beam that is 30 inches high, andcovered by a six inch thick floor, the width W at the region of greatestbulge may be only about inches, or about 7 percent greater than thewidth before form deformation. [n the types of beams commonly used inconcrete construction, a form construction which results in an increasedwidth of at least a few percent will urge the sides to spread by atleast a few degrees from their original position (which they have priorto pouring of concrete). The resulting tendency of the side walls tospread out will generally significantly reduce the effort required toremove the form. Of course, a variety of materials can be employed toconstruct the form besides fiberglass, so long as the form sides areresilient and will deform substantially when concrete is poured intothem. It is also desirable that the lower corners, such as 136, 138 beflexible, although the necessary deflection can occur even if thecorners are stiff. For beams of the type which have substantiallyparallel sides, the difficulty of form removal is especially great, andthe resiliently deformable form is especially useful. However, this formconstruction is also useful for beams with angled sides illustrated inFIG. 2.

Although particular embodiments of the invention have been described andillustrated herein, it is recognized that modifications and variationsmay readily occur to those skilled in the art and, consequently, it isintended that the claims be interpreted to cover such modifications andequivalents.

What is claimed is:

1. Apparatus for forming concrete structures including regions formingintegral'beams, floors, and columns comprising:

an elongated beam form with a bottom wall and side walls extending in agenerally upward direction from said bottom wall, the side walls at oneend of said form extending along the surface of an imaginary cylinder ofpredetermined diameter up to locations on diametrically opposite sidesof the cylinder, and said side walls have outwardly extending flanges attheir extreme ends; and

a column form for joining to said outwardly extending side wall ends ofsaid beam form to enclose the rest of said column region, to providecontinuous beam and column regions, said column form extending along thesurface of an imaginary cylinder of said predetermined diameter, andsaid column form having outwardly extending flanges for joining to theflanges on said beam form side walls.

1. Apparatus for forming concrete structures including regions formingintegral beams, floors, and columns comprising: an elongated beam formwith a bottom walL and side walls extending in a generally upwarddirection from said bottom wall, the side walls at one end of said formextending along the surface of an imaginary cylinder of predetermineddiameter up to locations on diametrically opposite sides of thecylinder, and said side walls have outwardly extending flanges at theirextreme ends; and a column form for joining to said outwardly extendingside wall ends of said beam form to enclose the rest of said columnregion, to provide continuous beam and column regions, said column formextending 180* along the surface of an imaginary cylinder of saidpredetermined diameter, and said column form having outwardly extendingflanges for joining to the flanges on said beam form side walls.